Problem: Daniel ate 3 slices of cake. Nadia ate 3 slices. If Daniel ate $\dfrac{3}{7}$ of the cake, what fraction of the cake was eaten?
Solution: If 3 slices represent $\dfrac{3}{7}$ of the cake, there must have been a total of 7 slices. $\text{fraction of cake eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ They ate ${6}$ out of $7$ slices. They ate $\dfrac{6}{7}$ of the cake.